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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
  <li><a href="#NOTES">NOTES</a></li>
  <li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>BN_mod_inverse - compute inverse modulo n</p>

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<pre><code>#include &lt;openssl/bn.h&gt;

BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
                       BN_CTX *ctx);</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>BN_mod_inverse() computes the inverse of <b>a</b> modulo <b>n</b> places the result in <b>r</b> (<code>(a*r)%n==1</code>). If <b>r</b> is NULL, a new <b>BIGNUM</b> is created.</p>

<p><b>ctx</b> is a previously allocated <b>BN_CTX</b> used for temporary variables. <b>r</b> may be the same <b>BIGNUM</b> as <b>a</b>.</p>

<h1 id="NOTES">NOTES</h1>

<p>It is an error to use the same <b>BIGNUM</b> as <b>n</b>.</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>BN_mod_inverse() returns the <b>BIGNUM</b> containing the inverse, and NULL on error. The error codes can be obtained by <a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>.</p>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>, <a href="../man3/BN_add.html">BN_add(3)</a></p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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